How Does the High-Latitude Thermal Forcing in One Hemisphere Affect the Other Hemisphere?

Abstract

Significant progress has been made in our understanding of extratropical impacts on the tropical climate via energetics framework. It is of question whether the impact of extratropical thermal forcing in one hemisphere would extend far into high-latitudes of the other hemisphere. We examine the possibility of the pole-to-pole linkage via atmospheric teleconnections by imposing a cyclic surface thermal forcing in the northern extratropics of an aquaplanet slab ocean model. We reveal a synchronous temperature response between the two poles mediated by zonal-mean atmospheric dynamics. A warming in one polar region leads to a strengthened Hadley circulation of the unforced hemisphere, fluxing more momentum toward the subtropics, thereby pulling the eddy-driven jet equatorward. A consequent anomalous descent over the polar region causes warming. The polar surface warming in the unforced hemisphere reaches 30% of that in the forced hemisphere, inferring a significance of the pole-to-pole connection.